The RD-861 () is a

Soviet The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

liquid propellant rocket engine burning a

hypergolic A hypergolic propellant is a rocket propellant combination used in a rocket engine, whose components spontaneously ignite when they come into contact with each other. The two propellant components usually consist of a fuel and an oxidizer. The ...

mixture of

unsymmetrical dimethylhydrazine Unsymmetrical dimethylhydrazine (abbreviated as UDMH; also known as 1,1-dimethylhydrazine, heptyl or Geptil) is a chemical compound with the formula H2NN(CH3)2 that is primarily used as a rocket propellant. At room temperature, UDMH is a colorle ...

(UDMH) fuel with

dinitrogen tetroxide Dinitrogen tetroxide, commonly referred to as nitrogen tetroxide (NTO), and occasionally (usually among ex-USSR/Russian rocket engineers) as amyl, is the chemical compound N2O4. It is a useful reagent in chemical synthesis. It forms an equilibrium ...

() oxidizer in a gas generator combustion cycle. It has a main combustion chamber, with four vernier nozzles fed by the gas generator output. It can be reignited a single time.

History

When the

military developed the Fractional Orbital Bombardment System, Yangel's

OKB-586 The ''Pivdenne'' Design Office (), located in Dnipro, Ukraine, is a designer of satellites and rockets, and formerly of Soviet Union, Soviet intercontinental ballistic missiles (ICBMs), established by Mikhail Yangel. During the Soviet era, the bu ...

proposed a new version of their R-36

ICBM An intercontinental ballistic missile (ICBM) is a ballistic missile with a range (aeronautics), range greater than , primarily designed for nuclear weapons delivery (delivering one or more Thermonuclear weapon, thermonuclear warheads). Conven ...

, called the R-36-ORB (

GRAU The Main Missile and Artillery Directorate of the Ministry of Defense of the Russian Federation (), commonly referred to by its transliterated acronym GRAU (), is a department of the Russian Ministry of Defense. It is subordinate to the Chief of ...

Index: 8K69). It incorporated an

orbit In celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an ...

warhead A warhead is the section of a device that contains the explosive agent or toxic (biological, chemical, or nuclear) material that is delivered by a missile, rocket (weapon), rocket, torpedo, or bomb. Classification Types of warheads include: *E ...

called OGCh (

Index: 8F021), for which the RD-854 engine was developed in-house. Since the

Outer Space Treaty The Outer Space Treaty, formally the Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies, is a Multilateralism, multilateral treaty that forms the bas ...

of 1967 banned nuclear weapons in Earth orbit, but did not ban the launch systems, the Soviet Union proceeded to test their FOBS albeit without placing nuclear warheads in orbit.

Versions

There are three versions of this engine: * RD-854 (

Index: 8D612): First developed as the third stage engine for the R-36ORB FOBS. * RD-861 (

Index: 11D25): Also known as the D-25. It was the engine of the Tsyklon-3 third stage. * RD-861K : An improved RD-861, developed for the third stage of the Tsyklon-4. The vernier nozzles were replaced with a hydraulic actuated

gimbal A gimbal is a pivoted support that permits rotation of an object about an axis. A set of three gimbals, one mounted on the other with orthogonal pivot axes, may be used to allow an object mounted on the innermost gimbal to remain independent of ...

for the whole engine. The isp was increased, the burn time tripled and the reignitions increased to three.

References

External links

Yuzhnoye Design Bureau English-language home page

Yuzhmash Home Page
Rocket engines using hypergolic propellant Rocket engines using the gas-generator cycle Rocket engines of the Soviet Union Yuzhnoye rocket engines Yuzhmash rocket engines Rocket engines of Ukraine {{rocket-stub

History

Versions

See also

References

External links